Scenery of Zhangjiajie national forest park in central China

The Yuanjiajie scenic area is seen in Zhangjiajie, central China's Hunan Province, April 18, 2017. Zhangjiajie is a famous tourist destination in Hunan Province. (Xinhua/Chen Yehua)

Tourists walk on a glass pavement in Tianmenshan scenic area in Zhangjiajie, central China's Hunan Province, April 19, 2017. Zhangjiajie is a famous tourist destination in Hunan Province. (Xinhua/Chen Yehua)

The hill roads are seen in Tianmenshan scenic area in Zhangjiajie, central China's Hunan Province, April 19, 2017. Zhangjiajie is a famous tourist destination in Hunan Province. (Xinhua/Chen Yehua)

The Tianmen Cave is seen in Tianmenshan scenic area in Zhangjiajie, central China's Hunan Province, April 19, 2017. Zhangjiajie is a famous tourist destination in Hunan Province. (Xinhua/Chen Yehua)